Telephone-exchange system



A. B. SPEBRY.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED JUNE 6,1918.

1,337,671, Patented Apr. 20, 1920.

Sr/ev/or To Opev.

Ari/7w .5. Saw Ky EUNITE STATES PATENT OFFICE.

ARTHUR 1B. SPERRY, OF NEW YORK, N. Y., :ASSIGNOR TO WESTERN ELECTRICCOMPANY, INCORPORATED, OF NEW YORK, N. 53., A CORPORATION NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

Application filed June 6, 1918.

$0 all w 7mm it mayconccrn Be it known that I, ARTHUR BL SrnRnY, a

control of both parties to an established con-' nection whereby eithermay cause the complete release of the switching means involved in theconnection.

Heretotore means whereby either party to an established connection maycause the release of the switches involved independently of the otherhas been provided but the present invention contemplates a moreetlicient arrangement employing a simpler and im proved circuit and anovel conception of means for performing this function.

In accordance with the main feature of the invention, a connectingcircuit is provided through which a call may be extended to an automaticexchange so arranged that, upon the establishment of a connection, abridge is closed across the incoming and another bridge across theoutgoing end of the connecting circuit. Each bridge controls a contactin the circuit of the other, and each is controlled by the subscriber oroperator at his end of the circuit so that either subscriber or operatormay control the opening of both bridges, whereupon the switches arerestored to normal.

In the embodiment of the invention di closed in the drawing, the callingline is an operators cord circuit by means of which a subscribers lineis manually extended to a distant automatic telephone exchange. However,it-will be obvious to those skilled in the art that the invention isequally well applicable to systems in whicha'n operators intervention isnot necessary to establish a connection.

Only so much is disclosed in the drawing as is necessary for a clearunderstanding of the invention. The apparatus and circuits employed inthe automatic telephone ex- Specification of Letters Patent.

Patented Apr. 20, 1920.

Serial No. 238,484.

change are the same as in the system disclosed in Patent No. 1,175,119to A. H. Blessing, with slight modifications in the connector circuit.

The operation of the system shown in the drawing is as follows:

A calling subscriber at station 1, desiring to obtain connection with acalled station 2, associated with a distant automatic exchange, causesthe operation of well-known means to extend his line to a manual operators cord circuit 3. The manual operator, having communicated with thecalling subscriber, inserts plug P into jack J. A trunk line i, 5terminating in jack J, leads to an operators position located at thedistant automatic exchange. The manual operator depresses her ringingkey RK, and connects an alternating current generator 6 and groundthrough the tip and ring contacts of plug P and ack J, trunk conductorsand 5, a condenser 7, and the left-hand winding of a relay D. The relayD becomes energized and closes a'locking circuit for itself from ground,through the armature and back Contact of a relay C, the armature, frontcontact, and the right-hand winding of relay D to grounded battery. Abranch of this circuit extends through a lamp L to grounded battery. Thelamp L is lighted and the automatic exchange operator is thus informedthat a call is awaiting attention at her position. She depresses herlistening key and causes the telephonic connection of her head-set (notshown) with the manual operators head-set. Having learned the number ofthe desired line, the a tomatic exchange operator actuates her he K,whereupon a calling device CD of the wellknown ty e is connected to theoutgoing end of her trunk a, 5. By means of the calling device, theoperator causes the setting of the first and second selectors and theconnector, in accordance with the numerical designa tion of the calledline. hen the connector switch is seized, the line relay LB becomesenergized and causes in turn the energize.- tion of relay 11 whichestablishes a holding circuit for relay 10 of the second selector. Byattracting its armature, relay 1O closes a holding circuit for relay 8of the first selector which relay is previously energized in a wellknown manner.

In response to the actuation e l a circuit is closed from ground, th*ougn contact k of key K and the right-hand winding of a relay A togrounded battery. The relay A becomes energized. When a relay 8 isenergized as above described, it connects ground through the conductor9, the contacts of a release key R, and the winding of a relay B togrounded battery, causing the energization of relay B. Relays A and B,being now energized, a bridge is closed across the incoming end of thetrunk conductors 4 and 5, which bridge extends from ground, through arelay 12, the tip contacts of plug P and jack J, conductor l, the innerfront'contact, armature and left-hand winding of relay A, right-handarmature and front'contact of relay B, the left-hand winding of therelay D, conductor 5, the ring contactsof jack J and plug P and thewinding'of relay 18 to grounded battery. Relays 12, 13, A and D arelocked up by current flowing through this circuit. Another bridge,closed by relays A and B across the outgoing end of the trunks, extendsfrom conductor a, through the normal contact of key K, the winding ofthe relay C, the lefthand front contact and armature of relay B, theouter front contact and armature of relay A, and the normal contact ofkey K to the conductor 5. This bridge is supplied with battery throughthe line relay LB oi the connector, and the lefthand armature and backcontact of a slow-acting relay 20.

hen the called party answers the call by removing his receiver from theswitchhook, therelay BB becomes energized, and causes in turn theenergization of a relay 21. The relay 21 closes an energizing circuitfor the relay 20, and the latter looks up through its right handarmature and front contact, and the right-hand armature and frontcontact of slow-acting relay 11. Upon the energiza tion ofthe relay 21and subsequent energization of relay 20, the second bridge extendsthrough 'the left-hand armature and front contact of relay 21. When therelay 0 becomes energized, it extinguishes lamp L and causes thelighting of lamp L which indicates that trunk 4,5 is energized.

When the connection is established,the relay A is under the control ofboth the distant manual exchange operator and the called line throughthe agency ofrelay B, and the re'layC is under the control of the calledline (through the agency of relay B), and the distant manual exchangeoperator (through the agency of the relay A).

When the called subscriber restores his receiver to the switchhoolt, therelay BB becomes deenergized and opens the circuits including relays 21,LR and C. The deene'rgization of relay LR results in the successivedeenergiaztion of relays 11, 20, 10, 8, and B. Under the control ofrelays 8, 10 and 11 the selectors and the connector are restored tonormal. Upon the deenergization of relay G the lamp L is extinguished.The relay B causes the opening of the bridge across the incoming end o1the trunk line, whereupon relays A, D, 12 and 13 become deenergized. Therelays 1 2 and 13 control well-known supervisory signals (not shown) atthe manual operators position. I

The clearing of the trunk under the control of the manual exchangeoperator, should she receive a clearing-out signal from the callingsubscriber before the called subscriber has replaced his receiver, isaccomplished by remoifing the plug P from the jack J. The lockingcircuit of the relays A and D being thereby opened, these relays be comedeenergized and the relay A opens the bridge across the outgoing end ofthe trunk. The relay C and the line relay LR of the connector becomedeenergized, whereupon the switcl es and the trunk circuit a, 5 arerestored to normal in the above described manner.

What is claimed is:

1. In a telephone exchange system, a calling and a called line, anoperators position, a trunk, means including automatic switching devicesfor establishing'a connection between said lines over said trunk,bridges across the incoming and outgoing ends of said trunk establishedwhen said connection is made, a relay at said operators position forcontrolling a'supervisory signal thereat, said relay being responsive tothe closing of said bridges, "means under the control of either thecalling or the called line for opening its bridge and therethrough openthe other bridge, andmeans for releasing said switching devices whensaid bridges are opened.

2. In a telephone exchange system, a calling and a called line, a trunk,means including automatic switching devices for establishing aconnection between said lines over said trunk, bridges across theincoming and outgoing ends of said trunk established when saidconnection is made, a relay through contacts ofwhich said bridgesextend, said relay being under the control of either line for openingone of said bridges and therethrough open the o'therbridge,;and meansfor releasing said automatic switching devices when said bridges areopened.

in witness whereof I hereunto'subscribe my name this 1st day of June, A.D.f1918.

ARTHUR B. SPEBRY.

